greenfield



UNITED STATES PATENT 5 OFFICE,

.EDWIN T. GREENFIELD, OF NEW YORK, N. r., AssIeNOR To Tint INTERIOR C ONDUIT AND INSULATION COMPANY, or SAME PLACE.

CON Duif-TUB E.

SPECIFICATION forming part of 'Letters Patent No. 570,169, dated october 27, 189e.

Application filed May 13, 1896. Serial No. 591,368. (llo'inodel.) *l

Toa/ZZ whom t may concern.-

,Be it known that I, EDWIN T; GREENFIELD, a citizen of the United States, residing at New York, in the county ofNew York and State of: New York, have made a new 'and luseful Invention in Conduit-Tubes, of which the following is a speciiieation. My invention is directed to improvements in armored conduit-tubes, such as are used Io for the purpose of protecting electrical conductors, and its object isto provide such conduits in which the insulation -onthe in'uer -side of .the conduit is made either wholly or in part of material which will fuse or liq'uefy u'nder abnormal temperatures with an interior lining of metalor other non-fusible or non-eombustible material.

In the use of armored conduits in bu-ildings and analogous plaeeswhere electrical 2o yconductors are protected by such conduits it often becomes necessary to locate the same in close proximityto steam-pipes or to fines,` hot-air shafts, and other places Where abnor mal heat occurs. Under these circumstances 2 5"it has been found. that where such armored` conduits are provided with an insulating-lining, either in whole or in part, which liquefies for abnormal heat the insulation breaks down and is in effect 'destroyedvandoftentimes at- 3o taches itself in liquid forni to' the inclosed conductor or conductors, thereby rendering vit impossible to withdraw them when necessary. It is also found that Where crosses ocour betWeenJthe conductors inclosed or Where there is abnormal current-leakagesufficient heat is generated to in a similar manner break .down or destroy the'insulation and also .to unite the conductors to the walls of the tube 4,through the agency of the liquefying nie- 4o dium. My invention eifectually overcolnes this trouble by firmly maintaining the insu] ating-lining against the inner Walls of the ar- Inored tube or pipe. My invention will be fully understood by referring to the accompanying d1awing,whicl1 is a longitudin al sectional View of two armored' my improved metallic lining located wit-hin said insulating-lining:

Referring no w tothe drawing in detail,vthe f armored cond uittubes, which are screwthreaded at their adjoining ends and united Aby a collar C, are composed of iron armor-P P,"insulatinglinings II, preferably .of paper treated with liquid asphalt, parain, or any Well-knowninsulating medium; or this inte- 6o rior liningmay be of pure asphalt or paraffin,

or any medium, either :in wholeor in part,. which will liquefy underabnormal temperatures. Y y My improvement terior insulating-lining I with a metallic or other non-fusible on non-combustible lining P', preferably of thinsheet-iron, although it may be ofV brass, copper, tin, or'any material which will not liquefy and which is not com- 7o i bustible under such.' temperatures as are found in the places indicated above or under such temperatures as result fromfan arc between 'any twoinclsed conductors. When y this interior lining is of'ironor lany other '75,

metal which is of comparatively high ind uct- -ive capacity-3l separate-the ends of the linings at the joints by definite spaces, as shown in the drawing, so as to overcome the inductive effect upon the inclosed conductors throughl8o. l

out a system in Whiehsueh conduits are used.'

I am'aware that it is not .broadly'new to line the interior of an armored yconduit with sheet-lead for the purpose of firmly holding the insulation against the inner Walls of the 85 conduit, such an arrangement having before been utilized in connection with a felt lining iuan iron-armored conduit and disclosed in United States patent to Tathaxn, No. 417,68S, granted December 17, 18,89, andiny claims 9o hereinafter made arey not designed to be broad enough to include such a conduit-tulw, the broadest scopevof the claims being directed to the utilization of a non-fusible or non-comlbustible interior lining for varmored 95,

vconduit-tubes' where the insulation, held botween the armor of the conduit-tubo and the interior lining, is either wholly or in part of a material which will fuse-or liquefy for teinperatures above 617 Fahrenheit, at which roo temperature lead will fuse, the inner or noncom'bustible non-fusible Wall of my inventionconsists in lining the inbeing designed to withstand such temperatures as are found in close proximity to fiues or chimneys or as are due to short circuits in great quantity or high tension systems of electrical conductors.

Having thus described my invention, what I claim, and desire to secure by Letters Patent of the United States, is-f 1. An armored conduit having an insulatinglining composed either wholly or in part of a material which liquefies at abnormal temperatures, in combination with a non-combustible non-liquefying interior lining adapted to withstand temperatures greater than the fusing temperature of lead, substantially as described.

2. An armored conduit-,tube consisting of a metal armor and an insulating-lining either in Whole 0r in part liquefiable under abnormal temperatures, in combination with an interior lining of a metal which will not fuse for such temperatures as will fuse or -liquefy either lead or thc insulating-lining.

3. A series of armored conduit-tubes lprovided cach with a lining which iseither wholl y or in part liquefiable at abnormal temperatures,v in combination with internal tubular linings for said armored tubes of an inductive metal such as iron, said linings being separated from each other by definite spaces, substantially as described.

4, An armored conduit-tube having an iron armor and an insulating-lining composed of paper or fibrous material treated with liquid asphalt under heat, in combination with an internal tubular lining of non-combustible non -liqueiable material, adapted to Withstand temperatures greater than the fusing temperature of lead substantially as described. l l

In testimony whereof I have hereunto subscribed my name this 12th day of May, 1806v EDWIN T. GREENFIELD.

XVitnesses: A

M. M. Roemsox, C. J. KINTNEP.. 

